I have constructed an HTPC using the following:
4u server case with quiet fans
Processor: P4 3.06 GHZ
Ram: 1 GB ram Dual Channel
Video Card: 512 MB Nvidia 6200 with DVI and Component out - 1280x720 timings passive cooling
Audio cards: Onboard realtek optical in and out and Envy 24 w/optical out
Frontends: Meedio TV and Media Portal
Dual DVD Burners
Decoders: NVDVD, WinDVD 7.0 Platinum Addition, Sonic Cineplayer, Meida Player 10
Wireless mouse and keyboard
14 inch LCD monitor for computing (located on coffee table)

This is connected to my HT that uses the following

LCR - Snell E-II's x3
Front Subs - 15 inch custom made with paradigm x30 crossover
Rear Subs - DCM Full Time subwoofers
Side speakers - Def Tech BP-1's
Rear Speakers - Radio Shack RCA specials (wll be replaced with another pair of BP-1's)
Processor - HK Citation 7.0 analog - Digital AC-3/DTS Technics SH-AC500D
Amps- 2 yamaha mx830's, dbx bx2, Yamaha p-2100
Routing - Inline 1424 line doubler (wIll be placed up for sale due to HTPC's scaling abilities)
Motorola HDTV Dual tuner DVR Cable box
Sharp HDTV LCD projector
Da-lite 106 inch 16:9 aspect ratio screen

Let me hear about whats out there